The magical reindeer nose

Every schoolchild knows about Rudolph the Reindeer and his magic red nose. But Rudolph’s real-life counterparts really do have a magic nose. The colder it is, the better it is in keeping the animals warm and hydrated.

The reindeer nose has a very large internal surface area, which allows it to warm cold air in record time. How is this possible? What’s nature’s secret recipe? Illustration photo: Per Harald Olsen

Reindeer live in harsh conditions during the winter. In Svalbard and on the fells and mountains of mainland Norway, temperatures sometimes drop to 30-40 degrees Celsius below zero. Little food is to be found when snow covers the landscape, and reindeer have to chew cold snow to get water. So how do reindeer survive when it’s so very cold?

Their thick fur is a good insulator, but that isn’t the whole explanation. Reindeer also survive by releasing as little heat as possible to the environment through their nose – and by conserving as much water vapour as possible.

What is it with Rudolph’s nose?

Does Rudolph’s nasal structure explain why reindeer do so well in cold climates?

This hypothesis interested PhD student Elisa Magnanelli and her NTNU supervisors, Signe Kjelstrup and Øivind Wilhelmsen, who also is an adjunct professor and researcher at SINTEF Energy Research. Their disciplines are thermodynamics and mass and heat exchange. But why would engineers be curious about animal respiratory systems? That will soon become clear.

Reindeer on treadmills

Magnanelli and her supervisors work closely with scientists at UiT—The Arctic University of Norway in Tromsø. The Tromsø researchers have brought real reindeer into a climate chamber and had them walk on a treadmill to study their respiration – all in the service of science. Measurements show that reindeer have a fantastic ability to change the temperature of the air they inhale before it reaches the lungs, and vice versa. If the outside air temperature is 40 degrees C below zero, the temperature when the air reaches the reindeer’s lungs is about 38 degrees C.

That means the reindeer’s ingenious nasal structure can change the temperature of the air an incredible 70-80 degrees in less than one second. On exhaling, the reindeer cools its warm breath instantly, in order to conserve as much body heat as possible.

Professor Signe Kjelstrup and her colleagues have long been interested in nature’s approach to different energy-efficient systems. Tromsø researcher Arnoldus Schytte Blix suggested she look into how reindeer handle extreme cold. Photo: NTNU

In addition, the reindeer breathes out minimal moisture when it exhales – which is especially important when the access to water is only snow, and icy snow at that.

Huge inner nose surface

The powerful reindeer snout is made up of cartilage and bone, fleshy structure, mucous membranes and lots of blood vessels. Researchers at UiT have taken internal measurements of the nose and done CT scans of reindeer nose slices. In this way, the researchers were able to acquire cross-sectional images of the reindeer’s breathing organ in its entire length. The pictures show that the nose interior has an unusual and strange structure that resembles a seashell.

Researchers also measured the inner surface area, which turned out to be enormous. Enormous in what way? Think of the Norwegian coast. If you measure the actual length of the coast, including all the nooks and crannies, you will find that the coastline is enormously long. This is what the inner surface of the reindeer’s nose is like as well. The expansive inner surface provides plenty of space for exchanging heat and water vapour between the air and the nasal wall.

What is nature’s recipe?

The illustration shows cross-sections of a reindeer nose. It clearly shows the complex structure of the nose, which looks like the cross section of a seashell.

So the nose has this very large internal surface, converting cold air to warm air in record time. How is this possible? What is nature’s secret recipe? Rudolph’s incredible ability to warm the air and control its humidity is an exciting topic for the NTNU researchers, who study thermodynamics and heat exchange.

Professor Kjelstrup and her colleagues have spent years studying energy-efficient systems. She began to speculate about whether nature itself could teach us something about energy efficiency, and contacted the Tromsø researcher Arnoldus Schytte Blix, who told her about the reindeer research.

Mathematical reindeer nose

The researchers decided to create a mathematical model of a reindeer’s nose. Magnanelli was assigned the task. She obtained several vital measurements from other research groups, including the researchers in Tromsø. These measurements included the amount of air a reindeer inhales when it breathes, blood flow rates and temperatures in different parts of the nose and the moisture content in the reindeer’s breath. The data were used both to develop and to assess the accuracy of a computer program specially designed to simulate a reindeer’s nose.

Data noses in the lab

In addition to creating a data-simulated reindeer nose, the scientists created a computer program of a simplified cylinder-like data nose that served as a reference case.

The researchers conducted repeated experiments in both data noses, with surprising results.

The picture shows a cross-section of a reindeer nose, with its complex seashell involutions. The structure makes for a huge surface area, allowing it to warm and cool air as needed and conserve moisture. Photo: Mario Acquarone

One finding showed that Rudolph’s nose can mostly be explained by the well-known theoretical principle of constant entropy production. The term could confuse the most avid lay reader without a quick explanation– so stay with us: When you go ice skating, you use some of your energy to overcome the friction that occurs between the ice and the skates. The friction generates heat under the skate blades, and energy is used. This is an example of the second law of thermodynamics.

But no real process is one hundred per cent energy efficient. Some friction always exists, which dissipates as heat into the surroundings. If you live in Svalbard or on Norway’s frigid Røros plateau, it’s important to lose the least amount of energy into the surroundings. Reindeer have clearly figured this out.

An ingenious design

Magnanelli’s simulation experiments, carried out 1600 kilometres and 15 degrees of latitude from the reindeer’s northernmost stomping grounds, shows that their nose mostly works according to the principle of minimum energy loss. This energy dissipation in the form of friction is what scientists call entropy production. The brilliant reindeer nose ensures that entropy production is nearly always uniform. This means that the animal as a whole loses the least possible amount of energy into the environment when it breathes. The reindeer nose roughly follows the mathematical “constant entropy production” equation.

To explain why this is so beneficial, consider the skating example. To use the least amount of energy to get around an ice rink, it’s best to maintain a steady speed. The same is true of reindeer noses – they’re designed to have close to uniform entropy production.

The colder the weather, the more effective the nose

The second finding that surprised the researchers is that the colder the air, the more energy efficient a reindeer’s nose is compared to a nose without the seashell shape. At 30 degrees C below zero, the reindeer’s seashell-shaped nose works even better than it does at 10 degrees below zero.

Between the mathematical nose model and the close-to-constant entropy production finding, NTNU researchers are now better able to explain how a reindeer’s nose works. The cold air is drawn in through the nostrils, passing over the large inner surface area. This surface consists of nasal mucus, located outside the fleshy nose structure and with many small blood vessels. The warm blood instantly and continuously heats up the mucus, which in turn heats the air being inhaled.

Øivind Wilhelmsen is Professor II at NTNU and a scientist at SINTEF Energy Research. He is one of Elisa Magnanelli’s supervisors.

Reindeer need to retain the water or moisture exhaled from the lungs so they don’t need to eat snow. And this illustrates another brilliant feature of nature: Winter air is cold and dry. In order for the heated air not to be too dry when it reaches the lungs, a little moisture is emitted from the mucous membranes into the air when the reindeer inhales. When the air is exhaled, the mucous membranes recover the moisture, so the reindeer exhales dry and partially cooled air.

Nature-based design

There are many reasons why scientists and engineers are eager to understand how the reindeer’s nose works. Reindeer noses serve as excellent heat and vapour exchangers because of their complicated seashell-like shape.

In fact, it’s entirely possible that this newly acquired knowledge may one day come in handy when industrial designers need to create balanced ventilation systems for homes and cottages in extremely cold climates. It may also provide an important contribution in building net-zero homes in the Arctic when the time is right.

In fact, it would probably be a perfect project for Santa’s workshop at the North Pole.

The arctic archipelago of Svalbard is already experiencing dramatic effects from climate change. A new study shows how these changes can force wild reindeer to graze on seaweed, a strategy that increases their likelihood of survival— and is recorded in their poop.

Climate change is increasing the likelihood of extreme winter rain events in the Arctic. These kinds of winter storms on Norway’s Svalbard archipelago can cause a thick cap of ice to cover the forage that reindeer eat. You’d think that more frequent rain-on-snow events would spell the end for these arctic animals — but you’d be wrong.

MORE NORWEGIAN SCITECH NEWS

LOADING CONTENT

Privacy Policy

The Privacy Statement is about how this website collects and uses visitor information. The statement contains information that you are entitled to when collecting information from our website, and general information about how we treat personal data.The legal owner of the website is the processing officer for the processing of personal data. It is voluntary for those who visit the web sites to provide personal information regarding services such as receiving newsletters and using the sharing and tip services. The treatment basis is the consent of the individual, unless otherwise specified.

1. Web analytics and cookies (cookies)

As an important part of the effort to create a user-friendly website, we look at the user pattern of those who visit the site. To analyze the information, we use the Google Analytics analysis tool.Google Analytics uses cookies (small text files that the site stores on the user's computer), which registers the users' IP address and provides information about the individual user's online movements. Examples of what the statistics give us answers to are; how many people visit different pages, how long the visit lasts, what websites users come from and what browsers are used. None of the cookies allow us to link information about your use of the site to you as an individual.The information collected by Google Analytics is stored on Google servers in the U.S.. The information received is subject to the Google Privacy Policy.An IP address is defined as a personal information because it can be traced back to a particular hardware and thus to an individual. We use Google Analytics's tracking code to anonymize the IP address before the information is stored and processed by Google. Thus, the stored IP address can not be used to identify the individual user.

2. Search

If the webpage has search function, it stores information about what keywords users use in Google Analytics. The purpose of the storage is to improve our information service. The search usage pattern is stored in aggregate form. Only the keyword is saved and they can not be linked to other information about the users, such as the IP addresses.

3. Share / Tips service

The "Share with others" feature can be used to forward links to the site by email, or to share the content of social networking. Tips for tips are not logged with us, but only used to add the tips to the community. However, we can not guarantee that the online community does not log this information. All such services should therefore be used wisely. If you use the email feature, we only use the provided email addresses to resend the message without any form of storage.

4. Newsletter

The website can send out newsletters by email if you have registered to receive this. In order for us to be able to send e-mail, you must register an e-mail address. Mailchimp is the data processor for the newsletter. The e-mail address is stored in a separate database, not shared with others and deleted when you unsubscribe. The e-mail address will also be deleted if we receive feedback that it is not active.

5. Registration, form

The website may have a form for registration, contact form or other form. These forms are available to the public to perform the tasks they are supposed to do.Registration form is for visitors to sign up or register.Contact form is for visitors to easily send a message to the website's contact person.We ask for the name of the sender and contact information for this. Personal information we receive is not used for purposes other than responding to the inquiry.The form is sent as email via Mailgun as a third party solution. The entire submission will be stored at Mailgun for 24 hours. Between 24 hours and 30 days, only mailheader is stored before the submission is deleted after 30 days. The reason for this storage is to confirm whether emails are sent from the website and forwarded to the correct recipient.Once the email is received by the recipient, it is up to the recipient to determine the data processing needs of the email.

6. Page and service functionality

Cookies are used in the operation and presentation of data from websites. Such cookies may contain language code information for languages ​​selected by the user. There may be cookies with information supporting the load balancing of the system, ensuring all users the best possible experience. For services that require login or search, cookies can be used to ensure that the service presents data to the right recipient.